Problem using date variable with date field

Hi all

Got a problem with assigning a date field to a date variable.

The procedure looks like this:

*   CREATE PROCEDURE TEST AS      
*     DECLARE VARIABLE DATEVAR DATE;
*   BEGIN
*     FOR
*       SELECT DATEFIELD
*       FROM   TABLE
*       INTO   :DATEVAR,
*     DO BEGIN
*       /* UPDATE THINGS  */
*     END
*   END

This gives me following error message:
*   "A fatal exception occurred during the execution of a user defined
function.
*   conversion error from string "23-AUG-2002"

Does anyone have any idea why this happens? (Yes, the field is defined
as date, i just double checked it (again).)

Thanks in advance!
Tom